Devices for controlling the speeds of motors are already known in the art. A wide range of such devices used various parameters as bases for adjusting the motor speed so as to correspond to a desired value.
However, in control loops for regulating the speed of motors, the parameters used as the bases for speed control have not been representative of the true speed of the motor. As a result, accurate speed control of a motor was not obtained, heretofore, because the basic parameter for controlling the speed was inaccurate.
Accordingly, it is an object of the present invention to provide an arrangement for controlling the speed of a motor, in which an accurate measure of the motor speed is obtained by sensing the back EMF of the motor.
Another object of the present invention is to provide an arrangement of the foregoing character which may be economically fabricated and maintained in service.
A further object of the present invention is to provide an arrangement as described which has a substantially long operating life.
A still further object of the present invention is to provide a motor speed control arrangement in which the speed of a motor in a tape recorder may be accurately maintained at a predetermined magnitude so as to result in precision recording and playback.